Hello guys. I have and issue with my tunze ato. What is happening is the pump will not turn on at all times. Happens on a pretty regular basis. When I unplug the head unit and plug back in it will start working like it should. It may go a few days if I'm lucky then resorts back to pump not coming on. The cycle starts over as I unplug the unit and restart. The pump is in a reservoir under the tank next to the sump where it distributes the water. Return line is not submerged and above water level. Any input would be appreciated. Thank you.